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Characterization by temperature programmed techniques of spent and acid treated vanadium catalysts
Charry,Iran David; González,Lina María; Montes de Correa,Consuelo;
Revista Facultad de Ingeniería Universidad de Antioquia , 2011,
Abstract: spent samples of v2o5/sio2-γal2o3 catalyst used for h2so4 production were acid treated to recover vanadium. fresh, spent, and acid treated samples were characterized by temperature-programmed techniques: tpr-h2, tpo-o2, tpd-nh3 and, tga-dta in order to determine the effect of deactivating species on vanadium recovery. drx and uv-vis techniques were used to confirm several signals from the temperature-programmed profiles. the results suggest that vanadium sulfovanadates and oxides in treated samples strongly interact with the support making it difficult to get more than 86% vanadium recovery.
Leaching of vanadium from sulphuric acid manufacture spent catalysts  [cached]
García, Diego Juan,Lozano Blanco, Luis Javier,Mulero Vivancos, María Dolores
Revista de Metalurgia , 2001,
Abstract: Recovery of vanadium contained in spent catalysts from the manufacture of sulphuric acid has been studied in this work, resulting in an industrial multistage process for the treatment of them avoiding direct deposition or dumping. Characterization of supplied spent catalysts samples, confirmed vanadium levels showed in the literature. The study of variables influencing leaching process: type of leaching agent, leaching agent concentration, S/L ratio, stirring speed and temperature, allows to fix the most advantageous conditions using industrial application criterion and verifying that the process is difusión controlled. The work is completed by developing an industrial leaching cycle simulation with the aim of reproducing real performance of spent catalyst, proposing operating conditions, and verifying the non-toxic character of the final residue obtained. En el presente trabajo se ha estudiado la recuperación del vanadio contenido en los catalizadores agotados procedentes de la fabricación del ácido sulfúrico, planteando un proceso industrial multietapa para el tratamiento de estos residuos, evitando su deposición o vertido directos. La caracterización de las muestras de catalizadores agotados disponibles confirmó los valores encontrados en la bibliografía. Se estudiaron las variables que influyen en el proceso de lixiviación (tipo de agente de lixiviación y concentración del mismo, relación S/L, velocidad de agitación y temperatura) definiendo las condiciones más adecuadas desde el punto de vista industrial y verificando que el proceso está controlado por mecanismos difusionales. El trabajo se completa con la simulación de un ciclo industrial de lavado del catalizador y la verificación de la nula toxicidad de los lixiviados obtenidos por degradación del residuo final. 24 Aplicación de la resistencia de ruido al estudio de pinturas ricas en zinc Noise resistance applied to the study of zinc rich paints
Recovery by solvent extraction of vanadium from spent catalysts leaching solutions using Primene 81R  [cached]
Lozano, L. J.,García, J.
Revista de Metalurgia , 2001,
Abstract: Recovery of vanadium contained in solutions coming from spent catalysts leaching process by means of solvent extraction techniques using primary amine Primene 81R, has been studied in this work, resulting in an industrial multistage process for the treatment of these effluents. Results obtained allows to propose an extraction mechanism for vanadium(V) with this amine in acidic media, verifying the great influence of pH on the process and fix adequate ranges for variables: O/A ratio, organic phase composition, pH, stirring speed and phase separation speed. These values were simulated in industrial conditions. Vanadium is finally recovered by means of precipitation as ammonium metavanadate and later calcination to obtain vanadium pentoxide of commercial grade. En el presente trabajo se ha estudiado la recuperación del vanadio contenido en soluciones procedentes del proceso de lixiviación de catalizadores agotados, por medio de la técnica de extracción con disolventes, empleando la amina primaria PRIMENE 81R, planteando un proceso industrial multietapa para el tratamiento de estos efluentes. Los resultados obtenidos permiten proponer un mecanismo de extracción para el vanadio(V), con esta amina en medio ácido, verificando la gran influencia del pH en el proceso y Ajando los rangos adecuados para las siguientes variables: relación O/A, composición de la fase orgánica, pH, velocidad de agitación y velocidad de separación de fases. Esos valores se simularon en condiciones industriales. El vanadio se recupera finalmente precipitándolo como metavanadato amónico y posterior calcinación para obtener pentóxido de vanadio de calidad comercial.
Development of a Continuous Kinetic Model for Catalytic Hydrodesulfurization of Bitumen  [PDF]
Farhad Khorasheh,Edward C. Chan,Murray R. Gray
Petroleum and Coal , 2005,
Abstract: Catalytic hydrocracking of topped Athabasca bitumen was investigated in a continuous stirred-basket reactor using a fresh and a spent commercial catalyst as well as in the presence of no catalyst. A continuous lumping model was used for kinetic analysis of hydrodesulfurization reactions. The normalized boiling point was used to describe the reactant mixture as a continuous mixture. The continuous model with only five adjustable parameters for hydrocracking and three adjustable parameters for desulfurization had good accuracy in the prediction of the weight percent of distillation fractions and their sulfur content in the products.
K. Ghanbari,M. Mohammadi,M. Tajerian
Petroleum and Coal , 2006,
Abstract: In kinetic study of catalytic reactions, due to mass transfer rate can be effective in adding to chemical kinetic, so it is necessary to study these effects firstly. The present work investigates the hydrodesulfurization of gas condensate, to determine the effect of interface mass transfer resistance. The entire work was performed in a hydrodesulfurization (HDS) pilot plant unit, located in Research Institute of Petroleum Industry (RIPI). For the tests, a commercial HDS catalyst (CoMo) was used and the feed (gas condensate) provided by South Pars gas field of Iran. The objective of the work was to investigate effect of mass transfer limitations in catalytic reaction of thiophene HDS. It was verified that mass transfer resistance has not a significant effect on the reaction rate. The results are presented as graphs and tables.
Removal of Vanadium(III) and Molybdenum(V) from Wastewater Using Posidonia oceanica (Tracheophyta) Biomass  [PDF]
Chiara Pennesi, Cecilia Totti, Francesca Beolchini
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076870
Abstract: The use of dried and re-hydrated biomass of the seagrass Posidonia oceanica was investigated as an alternative and –low-cost biomaterial for removal of vanadium(III) and molybdenum(V) from wastewaters. Initial characterisation of this biomaterial identified carboxylic groups on the cuticle as potentially responsible for cation sorption, and confirmed the toxic-metal bioaccumulation. The combined effects on biosorption performance of equilibrium pH and metal concentrations were investigated in an ideal single-metal system and in more real-life multicomponent systems. There were either with one metal (vanadium or molybdenum) and sodium nitrate, as representative of high ionic strength systems, or with the two metals (vanadium and molybdenum). For the single-metal solutions, the optimum was at pH 3, where a significant proportion of vanadium was removed (ca. 70%) while there was ca. 40% adsorption of molybdenum. The data obtained from the more real-life multicomponent systems showed that biosorption of one metal was improved both by the presence of the other metal and by high ionic strength, suggesting a synergistic effect on biosorption rather than competition. There data ware used for the development of a simple multi-metal equilibrium model based on the non-competitive Langmuir approach, which was successfully fitted to experimental data and represents a useful support tool for the prediction of biosorption performance in such real-life systems. Overall, the results suggest that biomass of P. oceanica can be used as an efficient biosorbent for removal of vanadium(III) and molybdenum(V) from aqueous solutions. This process thus offers an eco-compatible solution for the reuse of the waste material of leaves that accumulate on the beach due to both human activities and to storms at sea.
Hydrodesulfurization cobalt-based catalysts modified by gold
AM Venezia,R Murania,G Pantaleo,G Deganello
Gold Bulletin , 2007, DOI: 10.1007/BF03215569
Abstract: Cobalt catalysts supported on amorphous SiO2 and ordered mesoporous silica (MCM-41) were prepared by incipient wetness impregnation. Gold was added by consecutive impregnation or by co-impregnation. The materials were characterised by XPS, XRD and TPR techniques and evaluated in the hydrodesulfurization (HDS) of thiophene in order to investigate the effect of the noble metal on the structure and on the catalytic behaviour of the supported cobalt. Co/MCM-41 exhibited higher HDS activity and higher stability than the Co/SiO2. Moreover, in contrast to silica case, the gold impregnated MCM-41, produced an enhancement of the cobalt catalytic activity, and this is likely to be related to an increased cobalt reducibility. Both the support and the addition of gold improve the cobalt dispersion.
Peyman Mahinsa,Mohammad Taghi Sadeghi,Hamid Ganji
Petroleum and Coal , 2012,
Abstract: Catalyst pellets are one of the most important factors in catalytic reactor design. In this research a single catalyst pellet of hydrodesulfurization reaction have been investigated. The governing mass and energy balance equations have been solved numerically under steady state and dynamic conditions aiming to find the concentration and temperature profiles of the pelet. In order to consider the mass diffusion effect, the effectiveness factor η was introduced and solved at steady state mode.Sensitivity analysis with respect to the pellet surface conditions was studied in detail. Results showed that the effectiveness factor increases with surface concentration while it decreases as surface temperature increases. The Catalyst pellet was very sensitive to initial condition It was observed that decreasing the inlet concentration would increase the dimensionless concentration whereas the inlet concentration leads to a higher temperature.
Daniela Gulková,Luděk Kalu?a,Zdeněk Vít,Miroslav Zdra?il
Petroleum and Coal , 2009,
Abstract: The hydrodesulfurization of thiophene over ruthenium sulfide on Al2O3, MgO, SiO2, TiO2, ZrO2 oractive carbon was studied. The catalysts (1, 3 and 6 wt.% Ru) were prepared by impregnation withaqueous RuCl3. The only exception was the Ru/MgO catalyst which was prepared by impregnationwith methanolic solution of Ru acetylacetonate. The catalysts were sulfided either in a 10%H2S/H2or 20%H2S/N2 mixture at 400 oC. Their activity was tested at 400, 370 and 340 oC. The lattercatalysts were mostly more active than the former. The difference increased with the loading anddepended on support, the highest being with TiO2 and ZrO2 and the lowest with alumina and activecarbon. The Ru sulfide catalysts were more active than the Mo/Al2O3 catalyst with correspondingloading. The order of activity was independent of activation method and increased in the orderRu/MgO < Ru/Al2O3 ≈ Ru/SiO2 < Ru/ZrO2 < Ru/TiO2 < Ru/C.
Discovery of the Vanadium Isotopes  [PDF]
A. Shore,A. Fritsch,M. Heim,A. Schuh,M. Thoennessen
Physics , 2009, DOI: 10.1016/j.adt.2010.02.002
Abstract: Twenty-four vanadium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.
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